Door locking mechanism



April 16, 1957 w. F. WAGNER Erm. 2,788,997

DooR LOCKING MECHANISM Filed out. 22, 1954' url United States Patent DOOR LOCKING MECHANISM William F. Wagner, Los Angeles, and Charles E.

Cowdery, West Los Angeles, Calif., assignors to Northrop Aircraft, Inc., Hawthorne, Calif., a corporation of California Application October 22, 1954, VSerial No. 463,981

7 Claims. (Cl. 292-341.17)

This invention relates to spring action latches and more particularly to a spring latch adapted to secure and support heavy downwardly swinging horizontal doors.

One object of our invention is to provide a latch for holding and quickly releasing a jettison door in aircraft and other vehicles.

Another object of our invention is the provision of a spring latch that is adaptable to inspection plates, doors, windows, and closures of all kinds regardless of position in which they are mounted.

Another object of our invention is the provision of a latch mechanism adaptable for use with various objects, such as bombs, fuel tanks, stores, cells, rockets, landing gears, engines and the like, to render them releasable from their points of attachment through .means operated at positions of remote control.

Another object f our invention is to provide a latch of this type capable of supporting substantial weights and withstanding strong negative external pressures, yet substantially frictionless in operation regardless of the amount of tension involved.

Another object of our invention is the provision of a locking mechanism incorporating automatic means for properly positioning a keeper previous to engagement with a driving pawl.

A further object of our invention is the provision o locking mechanism having a minimum of parts.

In brief our invention comprises a load bearing latching mechanism including a rotatable disc, having disposed around the circumferential periphery thereof a plurality of outwardly extending-claw-like lobes spaced apart by sockets adapted to receive either one of two identical rollers, one being a strike member and attached to the dooror closure structure, the other being adapted to prevent reverse rotation of the disc and attached to a spring loaded pawl arm.

Closing of the door causes the strike roller to bear against one of the lobes of the keeper disc, thereby rotating the keeper disc and engaging the strike roller in the adjacent socket.

Simultaneously, rotation of the keeper disc causes the normallyv engaged pawl roller to move outwardly of one socket and into the next, thereby locking the strike roller and the door in closed attachment. A pivoted lever arm, adapted for operation from a remote point of control, is ittedwith an angular projection which, when the lever arm is moved, presses the pawl roller out of socketal engagement thus permitting the keeper disc to rotate backwardly and thereby ejecting the strike roller from socketal engagement and unlocking the door. Y

Additional objects of our invention will become apparent from the following description of one preferred embodiment of the latching mechanism which is illustrated diagrammatically in the accompanying drawings wherein:

lock mechanism, on the line 2-2 in lFigure 3.

Y23,788,997 Patented Apr. 16, 1957 rice Figure 3 is a cross sectional view taken on the line 3-3 in Figure 2.

Reference is again made to Figure l which shows diagrammatically the forward underbody of a transport aircraft 1 as seen from beneath with the right wing 2 in the upper foreground, with passenger and cargo area 3 in the fuselage 4. Beneath the wing 2 is a longitudinally disposed lateral extension of the fuselage 4 comprising an engine compartment 5 to which access is provided by two doors 6 and 7 having hinge lines paralleling the longitudinal axis of the aircraft and being equipped with remote release latches of the type covered by this application, positioned respectively as indicated at points 6a and 6b, and 7a and 7b.

A third door 8 with latch members 8a and 8b is centrally disposed in the underside of the fuselage and, being hinged along the forward spanwise side of the opening, swings downwardly through an axiodiametric arc of movement. This is the type of door best suited for cargo loading from ground vehicles and for jettisoning cargo and other objects during flight.

Attached to the under side of the Wing 2 is a droppable fuel cel-l 9 which is secured to a wing attachment plate 10 by means of slidably engaging offset brackets at the for Ward end and, centered in the rearward edge, a load bearing lock of the type described herein tted with a remote actuation releasing control.

The few diiferent methods of application of these locks are shown merely to suggest a variety of other purposes which it may be used to serve, and the limited number shown herein is not intended to limit the scope of our invention in any degree.

The latch mechanism itself, as seen in Figures 2 and 3 is enclosed in a U-shaped assembly case, which also serves as a mounting bracket, comprising a basal section 21 having parallel sidewalls 21a and 2lb disposed perpendicularly to the base making the assembly well adapted for mounting in a recess in the main structure along the edge of the door opening spaced from the hinge line. A transverse shaft 22 is mounted between the sidewalls 21a and 2lb on which operating lever arm 23 is 'adapted to rotate when actuating member 24 is placed under tension.

Unlike conventional bolt type latches and locks, the striker member in the lock of our invention is axed to the door and the keeper member which is attached to the fixed structure performs the movements required in the locking and releasing operations. In our mechanism the keeper which takes the place of the conventional movable latch bolt is actually a thick disc 25 adapted to rotate freely on shaft 22 and having a plurality of claw-like teeth or lobes 26 extending outward-ly from its circumferential periphery interspaced by concave sockets 27 which terminate inwardly in semicircular wall sections 28 dimensioned and conformed to iit snugly around movable roller detents in the manner illustrated at 29. The rollers 30 and 50 are interconnected to pawl arm 35 and door 8 respectively. These rollers restrain or cause to move keeper disc 25.

Roller detent 30, best seen in Figure 2, is adapted to rotate on stud 3i affixed to lower end of pawl Varm 35 which in turn is pivoted on transverse shaft 32 supported by sidewalls 21a and 2lb. The upper end of pawl arm 35, spaced from detent 3G is terminated in ayoke 33. The upwardly extended sides of yoke 33 have attachment straps 37a and 37b thereon. These pair of straps extend outwardly in parallel alignment from pressure cylinder 38, are pivoted and retained on the yoke 33 by means of studs 36a and 36h. As a result of the described structural arrangement the center of the yoke section is maintained open for lineal movement therethrough of piston rod 39rextending from piston 39p and pivotally attached to operating lever 23 at point 23x. Operating lever'23 is' journalled on transverse -shaft 22l and rotates thereon when actuating member 24, attached adjacent the. end of the`v lever spaced from the journal point, is placed under tension at some distant control point by means of a suitable knob, lever; pedal or-similar tensioning-meansA At the journal end of the operating lever a= projection 23p extendingy diagonally therefrom is provided with` a cam surface 23e which when levery is resting. against the stop 21s, is disposed:contiguously to roller detent'- 30 andi atA an anglesubstantially normali to the arc of movement of detent 30'when rotating about pivot=3 21 A helical compression spring 38sisldisposedwithin the cylinder 38 and serves/toexert-equalandco`realctive-pres Outward pressure sure upon both. ofthe detent rollers. of spring 33s, transmitted through piston rod 39; holds the lever-23 againststop 21's attached to sidewall-21a when operating lever 2-3isrnot undertension imposed by actuating member 24.

Roller 50is of substantiallythesame lengthand diameter as` pawl detent 30, andE is adapted to rotate upon a transverse shaftv 51- which is supported at each endy by-the sides of a generallyA rectangular, rigid, and hollow'enclosure or support bracket 56, Figure 2, having-a basal end member 52, parallelvand generally rectangular'side panels 53 and 54 and back panel 55, withthe topand front sectionsl being open above and below the strike roller 50 to receive` the portions of the keeper'disc lobes' extending outwardly of the door frame intothe opening occupied bythe door when closed.

In most cases, and particularly in the aircraft" door em bodiment being described herein, the supportl bracket 6 just described, would' be built inl as an integra-1 part' of the door structure and its design specifications would'be predicated upon the weightY of the door itself, the internal and external pressures to be encountered, and the dead'weight of cargo or other objects to be supported by the closure. Rollers 50 and 30l are disposed' equidistant4 from the axis 22` of` the keeper disc 25; and' substantially in the same horizontal plane.

Operation of the latching mechanism is simple andautomatic. strike roller 50 to enter a downwardly disposed. interlobular socket 27 in keeper disc 25 asshown in phantom at 50A, thereby rotating the, keeper disc counterclockwise and simultaneously forcing the pawl detent roller 30` out of the socket as at 30A which it occupied while the door was open. During the, nal movement induced by closing the door, the keeper disc 2S revolves to a position wherein the outer lobe 26 ofthe socket in which the strike, roller 50 is engaged has rotated counterclockwise and upwardly relative to the strike roller so as to prevent retraction thereof from engagement within the. socket 27 without reversing the rotation of the keeper disc. Backward rota,-` tion of the keeper disc 25 is prevented, however, by the spring, induced movement of'the pawl roller 30 into another disc socket 29newly indexed by the rotation O f the.

from further rotation, and thence through the mounting` bracket assembly 21, 21a and 2lb, to the mainstructure 4. They releasing operation is q uick and, positive, and the` movement of associated parts within the mechanismis concurrent rather than sequential. When actuating mem-- ber 24 is placed under tension at some point of remote control within the main structure, operating lever 23 rotates counterclockwise about pivot point 22 and the, cam surface 23C diagonally disposed along the outer edge of lever projection 23p bears against roller detent 30 forcing Closing the door as at 8A in Figure 2, causes the causes. thekeeper. disc 25- to, rotate clockwise under theweight of the door sustainedby the roller 50 which is engaged in a socket in the disc; Clockwise movement of the disc moves engagement lobe 26 downwardly permitting strike roller 50 to swing downwardly out of disc socket 27 when the socket reaches the. position indicated as 27A in Figure 2, thereby releasing'thedoor.

Codreactive spring loading etfective upon and equalized betweenthe pawl arm and theoperating lever by springl 38s in cylinder 38 causes all: ofthe mechanical'l elements to return to initial position when roller strike 5t0isv released and tension on actuating member 24 is relaxed, from their positions of, disp1acement 35A, 23Ay andA 38A respectively to their substantially untentioned normal positions of repose.

The nal step in the operative cycle is completed automatically when the pawl roller 30 returns to a position ofl engagement within oneofthe interlobular sockets of the keeper disc and therebyindexes another of theA keeper disc sockets` to thev diagonallyl downwardly and outwardly disposed strike-receiving position.

The foregoing description and the accompanying drawings clearly disclose one preferred embodimento our invention but it will be understood that this disclosure showing the mechanism adapted' to an aircraft door is purely illustrative of onlyl one ofthe many'use applications in which it may be employed; andthat such changes in the invention may be'made asare fairly withinthe scope of the-*following claims:

Whatl is claimedy is:

1. A- doork latch mechanism comprisingI a rotatable disc journalled to'stationarystructure along an inner edge of a door frame therein; said disc havingv disposedf about the edgewise circumferential' periphery thereof a plural,- itiy of: outwardly` extending claw-like lobes spaced apart byL concavefsockets; al longitudinally* extended pawla memberpvotedl intermediate its length to the main structure; detent member mounted on said pawl'. member and adapted for engagement in one of said' sockets of' said disc toprevent backward' rotation thereof; spring l'oad`- ing means for maintaining the positioning of the associated mechanical components; camming means for disengaging said pawl detent from said' disc socket to permit backward rotation of sai'dl disc; a. lever arm journalled coaxially' with' and adjacent to said disc; an actuating member attachedf to the endl thereof spaced' from said journalled end;-y a projection from one side of` saidlever arm adjacent said journal end; said projection having an outwardly extendedJ smooth edge diagonally disposed adjacent saidl paw1^d`etent,. said smooth edge being, effective asa cam surface to bear against said detentV and disengage it froml said* disc socket when sai'd lever arm is rotated by said actuating means.l

2. Apparatus in accordance with claim I wherein said springloading means comprise: a helically coiled springA disposed* within a longitudinally extended cylinder;A said'l cylinder being pivotally attached at the open end thereof to the outer end of' said pawl arm spaced' from said pawl detent roller; a piston slideable Within said cylinder and enteredv through the open end thereof, said piston having a rod extending outwardly therefrom and pivotally attached' to said lever arm adjacent the end spacedfrom said journalled end4 thereof,I whereby said coil spring is compressible between the bottoml of said cylinder and said. pistonv upon movement of said pawl detcnt and lever arm toward', cach. other.

3. Apparatus as set forth in claim 2, and additionally thereto, means adaptingI the spring tension for easy move.` ment during the, single action latching operating Cycle of the mechanism, comprising: a stop memben, fixedly attached to stationary structure. adjacent the outwardly extended end of sai'd` operating, lever and1 spaced from, the journal end., thereof; said Xcd stop being adapted to arrest rotation of said` lever atthe position wherein said cam surface is disposed contiguous to but not bearing against said pawl detent, whereby said lever remains immobile when the disc is rotated counterclockwise upon closing of said door, thus limiting the generating of spring compression to that imposed by the movement of said pawl detent outwardly from one of said disc` sockets and into the next.

4. In a lock mechanism having a rotary disc member, a pawl arm and detent to arrest rotation of said disc, a lever arm to release said disc member and spring loading means for maintaining positioning of components during periods of immobility as set forth in claim 2 and, additionally thereto, spring tension attaching means cornprising: a longitudinally extended cylinder, closed at one end and adapted to receive a piston and piston rod through the open end for slideable longitudinal movement therein; two attachment straps disposed diametrically opposite an outer surface of said cylinder adjacent said open end thereof; a yoke structure fxedly attached to the outwardly extended end of said pawl arm spaced from said pawl detent, the terminal portions of the two spaced members of said yoke structure being pivotally attached to two attachment straps oppositely attached to the periphery of said cylinder and said piston rod movable transversely between said pivotal attachments of said yoke ends and said cylinder attachment plates upon changes in spacing of said operating lever and said pawl arm.

5. A load bearing door latching mechanism comprising: a rotatable keeper disc, journalled to stationary structure along the inner face of the door frame therein, and having a plurality of evenly spaced outwardly extending claw-like lobes disposed about the circumferential periphery thereof, said lobes being interspaced by concave sockets semicircularly conformed at the innermost terminations thereof adjacent the axis of said disc; a pawl arm pivoted to said stationary structure, and having at one end a stud member xedly attached thereto, said stud member being disposed in axial alignment with said disc and having mounted thereon a roller member adapted for snug engagement within a disc socket whereby backward rotation of said disc is prevented.

6. A load bearing latching mechanism including the components and the relative positioning thereof as set forth in claim 5 together with additional means for absorbing stresses created by the weight of the door, comprising: journalling said operating lever coaxially with said rotary disc, providing the outwardly extended portion of said lever with a solid stop axed to the main structure and adapted to arrest the clockwise movement of said lever at a point at which said cam surface, diagonally disposed along the edge of said lever, is contiguotus to said pawl detent when said detent is seated in locked engagement within one of said sockets of said rotary disc and is positioned normal to the arc of rotation of said disc sockets at the over-center point at which said arc of rotation is intersected by the arc of rotation of said pawl detent, whereby said thrust force tending to rotate said disc into tighter binding engagement with said pawl member is transferred by said pawl member to said cam surface and thence through said lever journal and stop to said main structure.

7. A closure latch mechanism for structure comprising a body mounted on said structure; a shaft supported by said body; a ratchet wheel freely rotatable on said shaft; an elongated, spring loaded pawl cam pivotal on said shaft; a stop on said structure and overlying said roller detent against which said spring loaded pawl cam is engaged; a spring loaded lever pivotally mounted in said body; a roller detent on said lever, that is in linear alignment with said shaft and is received between the teeth of said ratchet when the closure is opened and closed; and means on said pawl cam for urging said cam from the stop engaging position.

References Cited in the le of this patent UNITEDY STATES PATENTS Roethel June 19, 1951 

